Closed Throttle Switch

The closed throttle switch is an integral part of the idle speed actuator (ISC) motor and provides an input voltage to the PCM. This input enables the PCM to increase or decrease the throttle stop angle (by extending or retracting the ISC) in response to the operating conditions.

TESTING

Eagle Throttle Body Fuel Injection (TBI) System

It is important that all testing be done with the Idle Speed Control (ISC) actuator motor plunger in the fully extended position, as it would be after normal engine shutdown. If it is necessary to extend the ISC motor plunger to test the switch, an ISC motor failure can be suspected.

With the ignition switch
ON
, test the switch voltage at the diagnostic connector terminals
D213
(+) and
D27
. The voltage should be close to zero at closed throttle and greater than 2 volts when off the closed throttle position.

If the voltage is always zero, test for a short circuit to ground in the wire harness or switch, or for an open circuit between PCM connector terminal
25
and the switch.

If the voltage is always more than 2 volts, test for an open circuit in the wire harness between the PCM and the switch connector, and between the switch connector and ground. Repair or replace the wire harness as necessary.

REMOVAL & INSTALLATION

Eagle Throttle Body Fuel Injection (TBI) System

The closed throttle switch is an integral part of the Idle Speed Control (ISC) motor; for removal and installation of the ISC motor, refer to the ISC motor procedure later in this section.